The present invention relates to a protection bag, so-called xe2x80x9ccurtain bagxe2x80x9d, for protecting a head of an automobile passenger. In particular, the present invention relates to a bag which inflates along a window in a side door when an automobile collides at a side thereof or turns over sideways. The present invention also relates to a protection apparatus for protecting a head of an automobile passenger by using the protection bag.
A curtain bag of this type, i.e. a protection bag for protecting a head of an automobile passenger, is disclosed in, for example, WO96/26087 in which a chamber unit includes a duct extending along an upper side of the bag from the front side of the automobile (front end) to the rear side of the automobile (rear end), and a number of cells or small chambers extending downward from the duct parallel to each other, each communicating with the duct.
In the bag which includes a number of small chambers extending downward parallel to each other, as the above known bag, a phenomenon occurs such that the bag expands while forming a vertically bent shape, i.e. V-shape in a longitudinal section, at the beginning of the expansion immediately after gas is introduced. In case small chambers, i.e. cells, which inflate first, are positioned toward an upper part of the bag according to the shape of a sewing line of the bag, a lower portion of the bag is bent to the inner side with respect to the restricting sewing line so as to form a V-shape in a longitudinal section. In case a large number of sewing lines in the transverse direction or ends of the sewing lines are positioned at an intermediate portion between the upper and lower edges of the bag, the bag is bent in a V-shape at the intermediate portion.
Due to the phenomenon in which the bag is bent in a V-shape (hereinafter referred to as a xe2x80x9cfolding phenomenonxe2x80x9d), complete downward extension of the lower end of the bag is delayed.
Generally, since the gas flows straight in a duct at a predetermined speed while thermally expanding, the gas tends to flow straight rather than changing the direction quickly to flow at a right angle toward the small chambers in the known curtain bag in which the relatively long small chambers extend downward from the duct in a direction perpendicular to the duct. The gas which flows straight rebounds when it collides against a sealed end of the duct. The rebounding gas collides with the straight flowing gas, so that the speed of the flowing gas is set off, thereby reducing the initial speed of the gas. Due to internal pressure rise in the vicinity of the collision, the gas tends to flow toward a portion where the pressure is low, that is, toward the small chambers, so that the direction of flow of the gas changes at a right angle. In the known curtain bag in which the direction of flow of the gas reduced in pressure by the collision is changed at a right angle when the gas flows into the small chambers, the efficiency of inflation of the bag is low because of the significant loss in the speed of the gas.
It is a first object of the present invention to provide a protection bag for a head of an automobile passenger, in which the bag remains in an inflated state for a long time after being inflated.
It is a second object of the present invention to provide a curtain bag, wherein an ability of expanding quickly is improved.
It is a third object of the present invention to provide a curtain bag which has a high energy absorbing effect of absorbing collision energy generated when the passenger""s head collides with the curtain bag.
According to a first aspect of the present invention, a protection bag for protecting a head of an automobile passenger is disposed in the vicinity of a corner between a ceiling and a side face of an automobile. The bag inflates downward along the side face as gas is introduced, and is formed of a plurality of small chambers in the bag, wherein at least one of the small chambers is bent or curved in a direction of flow of the gas.
The small chamber which is bent may include a gas inlet at one end, or alternatively, at one end and at the other end of the small chamber, and the direction of flow of the gas may be defined as a central line connecting the one end and the other end through the intermediate points in the lateral direction of the small chamber. The length of the central line connecting the one end and the other end is preferably greater than a maximum width in a direction perpendicular to the central line or the tangent to the central line.
The width in a direction perpendicular to the central line is defined as a width of the bag, when it is not inflated and spread in a plane.
The small chamber which is bent in a direction of flow of the gas is preferably bent or cured, for example, into a J-shape, a C-shape, or an S-shape.
In the bag or curtain bag, the gas is not likely to return to the gas inlet side from the small chamber when the passenger""s head collides with the inflated bag, so that the gas is not likely to flow out from the small chamber, thereby sufficiently absorbing the impact.
When the direction of flow of the gas is gradually changed so as not to reduce the speed of flow of the gas by disposing the small chamber which is elongated in the direction of flow of the gas and is curved so as not to be sharply bent, the loss of the speed of flow of the gas is reduced, and the gas flows through the small chamber at a high speed. Thus, the curtain bag has a high ability of quickly expanding.
Particularly, it is significantly efficient when the small chamber is formed in a spiral form.
That is, when the small chamber is formed in a spiral form, the length in a direction of flow of the gas of the small chamber can be made long, thereby increasing the volume of gas which can be introduced into the small chamber. Therefore, the volume of gas which moves when the passenger""s head collides with the small chamber is increased, so that a high energy-absorbing (hereinafter abbreviated to xe2x80x9cEAxe2x80x9d) effect can be obtained. When the small chamber is formed in the spiral form, the tensile forces to be applied to a sewing line is generated at an angle of 360xc2x0. Thus, the tensile forces can be distributed to sections of a wide range in the bag, and a high EA effect is obtained. When the passenger""s head collides with the spiral-shaped small chamber, gas-flowing path elongated in a direction of flow of the gas is closed by pressing the small chamber at a plurality of portions thereof, thereby narrowing the gas outlet, so that the gas is not likely to flow out. Therefore, it is significantly efficient as a high EA effect is obtainable.
According to the first aspect of the present invention, at least one of the small chambers which is bent or curved in a direction of flow of the gas may include an extending member which is disposed so as to extend in the longitudinal direction of the automobile. Since the extending or elongated member is not likely to be bent at a vertically intermediate portion thereof, the passenger""s head is efficiently held so as to be protected from the impact from the inside of the automobile, by the extending member which is supported by two pillars when the passenger collides with the extending member at the head.
According to a second aspect of the present invention, a protection bag for protecting a head of an automobile-passenger is disposed in the vicinity of a corner between a ceiling and a side face of an automobile, and inflates downward along the side face as gas is introduced. The protection bag comprises a plurality of small chambers in the bag, wherein at least one of the small chambers is provided with a gas inlet which is positioned at an upper part of the bag, the small chamber continuing from the gas inlet to a lower side of the bag.
In the protection bag for protecting a head of an automobile passenger, a gas-introducing chamber is preferably provided to extend along an upper side of the bag, and a gas outlet provided in the gas-introducing chamber is preferably disposed so that the gas outlet faces the gas inlet of the small chamber. In particular, the gas inlet is preferably connected directly to the gas outlet.
The cross-sectional area of a gas-flowing path connected to the gas inlet of each small chamber is preferably set so that the speed of expansion of the small chamber is substantially the same as that of the other. With this arrangement, each small chamber inflates so as to expand substantially simultaneously with the other, whereby a bag is well balanced in the timing of expansion.
The protection bag, according to the present invention, may further comprise a duct provided along an upper side of the bag, through which the gas from an inflator flows, for distributing the gas between the small chambers. The duct may be provided with a bent part which is bent downward in the middle of the duct.
In the protection bag for protecting a head of an automobile passenger, a portion of the gas flows from the bent part toward the lower side of the bag. With the gas flowing to the lower end of the bag, the bag quickly expands downward without being folded.
In this case, at least one gas inlet of the small chamber is preferably disposed in the vicinity of the bent part. With this arrangement, the gas, the direction of which changes downward at the bent part, is likely to flow directly into the small chamber.
A protection apparatus for protecting a head of an automobile passenger according to the present invention comprises the protection bag thus arranged and a gas generator for supplying the gas into the protection bag.